Abrading device



s. TRINKLE 2178.381

ABRADING mines Filed April 2a, 1938 INVENTOR Patented Oct. 31, 1939ABRADING D'EVICE Carl Trinkle, Cincinnati, Baldwin Company,

Ohio, assignor to The Cincinnati, Ohio Application April 2s, 1938,Serial No. 204,365 5 Claims. (01.. 51-187) My invention has reference tomeans relating to abrading methods and more particularly to abradingprocesses employing liquids with the abrading substances. These wetprocesses of abrading, so called, are especially advantageous infinishing metals, such for example as stainless steel, aluminum andthelike, and article surfaces precoated with lacquers, varnishes, enamelsor the like, to provide them with pleasing decorative appearance. Theprocesses are often carried out by partially enclosing a suitable blockor pad in a sheet of abrasive paper, with the abrading surface exposed,and rubbing the article surface with it, periodically dipping theabrasive sheet and its hacking into a liquid such as water or benzine.

The use of a liquid in fine abrasive finishing is advantageous, and inmy opinion it acts both as a lubricative cooling agent to prevent localheating of the work and as a'distributant for the abraded particles, toprevent their agglomeration. It also reduces the loading of the abrasivesheet.

As carried out with the usual means for wet abrading, the rubbing of thearticle surface squeezes the liquid out from under the abrasive sheetand pushes it out of the path of operation. This drying of the workresults in chattering or jumping of the abrading device thereon, with aconsequent loss of time and annoyance to the operator, requiringfrequent replenishment of the liquid. Moreover it reduces theprobability of a high class of finishing. Again, during the wetabrading, abraded materials such as a sludge of lacquer or the likeaccumulates unevenly on the surface of the paper, impairs its action,and is so difiicultly removable that the paper is usually thrown awayinstead of being salvaged as by scrubbing.

The general objects of my invention are the provision of anabrading'means, structure and process whereby the disadvantages setforth above are obviated, and whereby the work is facilitated andshortened, the materials made to last much longer, and the severaladvantages attained without cost.

The attainment of these objects and other objects which will be apparentto those skilled in the art onreading this specification, I accomplishby that certan. construction and process of which I shall now set forthcertain exemplary embodiments, reference being made, for clearness, tothe drawing forming a part hereof. In the drawing, wherein all views arein perspective:

Figure 1 shows anabrasive sheet constructed 55 according to theinvention;

Figure 2 represents a pad;

' Figure 3 shows the combination of the sheet of Figure 1 and the pad ofFigure 2;

Figure 4 is a view of a holding block;

Figure 5 shows the combination of the block of Figure l and the sheetand pad of Figures 1 and 2, respectively; and

Figure 6 shows a modified'form of sheet construction.

I have made the discovery that if a paper or cloth surfaced with anabrasive suitable for wet abrading processes is perforated at intervalsand is used in connection with a polishing block surfaced wlth absorbentsubstance such as felt, the Whole being dipped into the liquid vehicle,two 1 simultaneous actions occur during the course of the rubbing: Firstthe liquid continues to feed through the perforations in the paper, soas to maintain at all times a film of liquid on the work. Even withhighly volatile liquids, the film can be maintained with one dippingusually far longer than necessary to complete the rubbing cycle. Thuschattering or jumping of the rubbing device is prevented, and a superiorfinish is obtained. Second, at the same time the sludge produced by therubbing goes into the holes in the abrasive sheet in countercurrent tothe liquid, so that all sludge is either collected in these holes oraccumulates beyond the edges of the abrasive sheet at the end portionsof the rubbing stroke. The efflux of the liquid through the holes doesnot interfere with the entrance and collection of the sludge in theholes, nor does the liquid tend to spread the sludge over the surface ofthe abrasive sheet. At the conclusion of the rubbing cycle the surfaceof the abrasive sheet will be found quite clean; and the abrasive devicemay be redipped and reused until the abrasive is wholly worn away.

All of these factors tend to shorten the rubbing operation, and make thecutting action much more efficient.

Thus in one form of sheet construction, as in Figure l, a sheet ofsmooth paper I is coated with finely divided aluminum oxide 2 attachedto the sheet by suitable cement, and interspacedin the sheet are aplurality of openings such as the holes 3 for liquid transmissivity. Myinvention is not limited to any particular abrasive material; hence theterm aluminum oxide is to be construed as meaning any suitable abradant,reduced to the required fineness according to the character of the workto be done; similarly, the word paper is to be construed as meaning anysheet comprising a porous liquid-absorbent member and to which anabradant may be attached. In Figure 2 is shown an absorbent pad 4 whichmay be of felt, cloth, absorbent paper or the like ca.- pable of storingliquid, and in Figure 3 this pad or backing 4 is combined byjuxtaposition with the sheet I, with the abradant 2 exposed, to form anabrading device of the invention.

As a convenient means for holding an abrasive sheet, a block 5 (Figure4) may be of rubber, wood or the like and has slots 6 and 1, one on eachside as shown. The edges of the sheet I may be placed in these slotswith the pad 4 between the sheet and block, as shown in Figure 5, toform an abrading device operative according to the invention, in whichthe abrasive sheet may be readily disengageably attached to theabsorbent backing 4, 5.

In a modified form of sheet construction, Figure 6, a sheet of cloth 8is coated with abrasive particles, but in interspaced areas 9 of thecloth the cement for adherence of the coating has been omitted, and inthese areas 9 the porosity of the cloth permits transmissivity ofliquid.

In practicing my invention, I have found that the best finishes onarticle surfaces are obtained when the abrasive particles of theabrasive sheet are not larger than will pass through a 240 mesh screen.Moreover it is not advantageous to employ liquid transmissive areas inthe sheet, of less than an equivalent hole diameter of inch, nor toprovide a total liquid transmissive area in excess of per cent. of thesheet area.

The present device may be modified in form and construction within thespirit of the invention. It may be of various sizes suitable for machineor manual use. Accordingly the scope of the invention is pointed out inthe appended claims and having thus described my invention, I claim:

1. A rubbing pad for wet abrasive finishing an abrasive sheet havingperforations therethrough and backed by said member so that when wettedsaid member causes liquid to feed through said perforations in saidsheet when said pad is applied as an abrasive means in a wet abrasivefinishing operation.

2. A rubbing pad for wet abrasive finishing comprising a porousliquid-absorbent member and an abrasive sheet having areas transmissiveof liquid therethrough and backed by said member so that when wettedsaid member causes liquid to feed through said perforations in saidsheet when said pad is applied as an abrasive means in a wet abrasivefinishing operation.

3. A rubbing pad for wet abrasive finishing comprising a porousliquid-absorbent member and a sheet of suitable paper havingperforations therethrough and having a coating thereon of suitableabrasive particles cemented thereto of a size that will pass through a240 mesh screen, said sheet being backed by said member so that whenwetted said member causes liquid to feed through said perforations insaid sheet when said pad is applied as an abrasive means in a wetabrasive finishing operation.

4. A method of wet abrasive finishing which comprises cementing acoating of suitable abrasive particles to a suitable sheet as a base andproviding areas transmissive of liquid there through at intervals insaid coating and said sheet, backing said sheet with a porousliquidabsorbent member, Wetting said member with a suitable liquid, andrubbing a surface to be finished by wet abrasion with said sheet asbacked by said member.

5. A method of wet abrasive finishing which comprises cementing to asuitable sheet of paper a coating of suitable abrasive particles of asize that will pass through a 240 mesh screen and providing perforationsat intervals in said coating and said sheet, backing said sheet with aporous liquid-absorbent member, wetting said member with a suitableliquid, and rubbing a surface to be finished by wet abrasion with saidsheet as backed by said member.

CARL TRINKLE.

